U.S. patent number 11,398,191 [Application Number 16/562,057] was granted by the patent office on 2022-07-26 for timing controller, organic light-emitting display apparatus, and driving method thereof.
This patent grant is currently assigned to LG Display Co., Ltd.. The grantee listed for this patent is LG DISPLAY CO., LTD.. Invention is credited to Youngchan Kim, Jaehwan Yun.
United States Patent |
11,398,191 |
Kim , et al. |
July 26, 2022 |
Timing controller, organic light-emitting display apparatus, and
driving method thereof
Abstract
An organic light-emitting display device includes: a display
panel in which a plurality of data lines and a plurality of gate
lines are arranged to overlap each other and that includes a
plurality of subpixels which are arranged in areas in which the
plurality of data lines and the plurality of gate lines overlap
each other; a data driver that supplies a data signal to the
plurality of data lines; a gate driver that supplies a gate signal
to the plurality of gate lines; and a timing controller that
controls the data driver and the gate driver such that the data
driver outputs a sensing voltage in a first section, outputs a
compensation voltage in a second section, and outputs a data
voltage in a third section.
Inventors: |
Kim; Youngchan (Gyeonggi-do,
KR), Yun; Jaehwan (Gyeonggi-do, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
LG DISPLAY CO., LTD. |
Seoul |
N/A |
KR |
|
|
Assignee: |
LG Display Co., Ltd. (Seoul,
KR)
|
Family
ID: |
1000006456008 |
Appl.
No.: |
16/562,057 |
Filed: |
September 5, 2019 |
Prior Publication Data
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|
|
|
Document
Identifier |
Publication Date |
|
US 20200074939 A1 |
Mar 5, 2020 |
|
Foreign Application Priority Data
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|
|
|
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Sep 5, 2018 [KR] |
|
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10-2018-0105745 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G09G
3/3233 (20130101); G09G 3/3258 (20130101); G09G
3/3291 (20130101); G09G 2320/103 (20130101); G09G
2310/027 (20130101); G09G 2310/08 (20130101); G09G
2360/18 (20130101); G09G 2300/0842 (20130101); G09G
2320/045 (20130101); G09G 2320/0257 (20130101) |
Current International
Class: |
G09G
3/3291 (20160101); G09G 3/3233 (20160101); G09G
3/3258 (20160101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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102334153 |
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Jan 2012 |
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CN |
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103886831 |
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Jun 2014 |
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CN |
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104700772 |
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Jun 2015 |
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CN |
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105513541 |
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Apr 2016 |
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CN |
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105741733 |
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Jul 2016 |
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CN |
|
106560882 |
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Apr 2017 |
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CN |
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106847171 |
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Jun 2017 |
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CN |
|
106991965 |
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Jul 2017 |
|
CN |
|
107068065 |
|
Aug 2017 |
|
CN |
|
107799063 |
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Mar 2018 |
|
CN |
|
Primary Examiner: Flores; Roberto W
Attorney, Agent or Firm: Seep IP Law Group LLP
Claims
What is claimed is:
1. An organic light-emitting display device, comprising: a display
panel in which a plurality of data lines and a plurality of gate
lines are arranged to overlap each other and includes a plurality
of subpixels which are adjacently arranged in areas in which the
plurality of data lines and the plurality of gate lines overlap
each other; a data driver that supplies a data signal to the
plurality of data lines; a gate driver that supplies a gate signal
to the plurality of gate lines; and a timing controller that
controls the data driver and the gate driver to cause the data
driver to output black data during an initial section of a frame,
output a sensing voltage through the plurality of data lines during
a first section, output a compensation voltage during a second
section, and output a data voltage during a third section, wherein
the initial section, the first section, the second section, and the
third section are contiguous within the frame, wherein a voltage
level of the compensation voltage corresponds to a voltage level of
the data signal, wherein each of the plurality of subpixels
includes: a first transistor in which a first electrode is
electrically connected to a first node electrically connected to a
first power supply line to which a high-potential voltage is
supplied, a gate electrode is electrically connected to a second
node, and a second electrode is electrically connected to a third
node; a second transistor in which a first electrode is
electrically connected to the corresponding data line, a gate
electrode is electrically connected to the corresponding gate line,
and a second electrode is electrically connected to the second
node; a third transistor in which a first electrode is electrically
connected to the third node, a gate electrode is electrically
connected to a sensing signal line, and a second electrode is
electrically connected to a second power supply line for supplying
an initialization voltage; a capacitor that is electrically
connected between the second node and the third node; and an
organic light emitting diode in which a first electrode is
electrically connected to the third node and a second electrode is
electrically connected to a low-potential voltage, the organic
light emitting diode having a threshold voltage, wherein the data
line supplies the sensing voltage and the second power supply line
supplies the initialization voltage in the first section, the data
line supplies the compensation voltage in the second section, the
data line supplies the data voltage in the third section, wherein
when the second transistor is turned on, the data line supplies the
sensing voltage to charge the second node and when the third
transistor is turned on, the second power supply line supplies the
initialization voltage to charge the third node, wherein when the
second transistor is turned off and the second power supply line is
electrically disconnected, the second node and the third node are
in a floating state, wherein the first transistor allows a sensing
current to flow to the second power supply line via the third
transistor, and a voltage level of the third node increases based
on the sensing current at a certain slope indicative of an electron
mobility of the first transistor, wherein the timing controller
includes an image analyzing circuit that includes a frame memory
configured to store image data for each frame and a data processing
circuit configured to extract first data corresponding to a first
line of the display panel from the image data and to determine the
voltage level of the compensation voltage on the basis of the first
data, and wherein the sensing voltage is maintained constant during
the first section at a first voltage level that is lower than the
threshold voltage of the organic light emitting diode.
2. The organic light-emitting display device according to claim 1,
wherein the image analyzing circuit includes a lookup table in
which the voltage level of the compensation voltage is set for a
grayscale value corresponding to the voltage level of the data
signal.
3. The organic light-emitting display device according to claim 1,
wherein the timing controller is supplied with information on the
voltage level of the compensation voltage from the image analyzing
circuit.
4. The organic light-emitting display device according to claim 1,
wherein the data driver further includes an analog-digital
converter and the analog-digital converter, and is supplied with a
voltage of the third node in the first section.
5. The organic light-emitting display device according to claim 4,
wherein the timing controller supplies an image signal to the data
driver such that the image signal is corrected on the basis of the
voltage of the third node and is supplied to the data driver.
6. The organic light-emitting display device according to claim 1,
wherein the initial section in time precedes the first section in
time, the first section in time precedes the second section in
time, and the second section in time precedes the third section in
time.
7. The organic light-emitting display device according to claim 1,
wherein a voltage level of the black data during the initial
section is lower than a voltage level of the sensing voltage during
the first section.
8. The organic light-emitting display device according to claim 7,
wherein the voltage level of the sensing voltage during the first
section is lower than a voltage level of the compensation voltage
during the second section.
9. The organic light-emitting display device according to claim 7,
wherein the voltage level of the sensing voltage during the first
section is greater than a voltage level of the compensation voltage
during the second section.
10. The organic light-emitting display device according to claim 9,
wherein the voltage level of the compensation voltage during the
second section is greater than the voltage level of the black data
during the initial section.
11. The organic light-emitting display device according to claim 1,
wherein, when the first voltage level of the sensing voltage that
is lower than the threshold voltage of the organic light emitting
diode is supplied to the organic light emitting diode, the organic
light emitting diode does not emit light.
Description
CROSS REFERENCE TO RELATED APPLICATION
This application claims priority from Korean Patent Application No.
10-2018-0105745, filed Sep. 5, 2018, which is hereby incorporated
by reference for all purposes as if fully set forth herein.
BACKGROUND
Technical Field
Embodiments of the present disclosure relate to a timing
controller, an organic light-emitting display device, and a driving
method thereof.
Description of the Related Art
With advancement in information-oriented societies, requirements
for display devices displaying an image have increased in various
types, and various types of flat-panel display devices such as a
liquid crystal display device, a plasma display device, and an
organic light-emitting display device have emerged.
Recently, organic light-emitting display devices which can be
easily decreased in thickness and which are excellent in viewing
angle and contrast range, and the like have widely utilized. An
organic light-emitting display device emits light to display an
image by supplying a drive current to organic light emitting diodes
which are spontaneous light emitting elements. When an organic
light emitting diode emits light for a long time, deterioration
occurs. Deterioration can be more likely to occur, particularly,
when a still image with high luminance is displayed. An organic
light emitting diode can cause a problem in that an afterimage
appears to shorten a lifespan thereof due to deterioration.
A difference in threshold voltage can occur between driving
transistors that supply a drive current to organic light emitting
diodes due to a process deviation and thus a difference in drive
current can occur between subpixels. The drive current can deviate
depending on electron mobility. When a deviation in drive current
occurs, there is a problem in that luminance becomes uneven and
image quality degrades.
BRIEF SUMMARY
One or more embodiments of the present disclosure provide a timing
controller, an organic light-emitting display device, and a driving
method thereof that can prevent a degradation in image quality. The
organic light-emitting display device according to one or more
embodiments of the present disclosure senses characteristics based
on threshold voltage and electron mobility to prevent uneven
display on the device.
According to an aspect of embodiments of the disclosure, there is
provided an organic light-emitting display device including: a
display panel in which a plurality of data lines and a plurality of
gate lines are arranged to overlap each other and that includes a
plurality of subpixels which are arranged in areas in which the
plurality of data lines and the plurality of gate lines overlap
each other; a data driver that supplies a data signal to the
plurality of data lines; a gate driver that supplies a gate signal
to the plurality of gate lines; and a timing controller that
controls the data driver and the gate driver such that the data
driver outputs a sensing voltage in a first section, outputs a
compensation voltage in a second section, and outputs a data
voltage in a third section.
According to another aspect of embodiments of the disclosure, there
is provided a timing controller circuit including: a data
extracting unit configured to extract image data which is stored in
a frame memory; a lookup table configured to store compensation
voltage information on a voltage level of a compensation voltage
corresponding to the image data; and a data processing unit
configured to be supplied with the compensation voltage information
on the voltage level of the compensation voltage from the lookup
table depending on the image data extracted by the data extracting
unit and to output the compensation voltage information.
According to another aspect of embodiments of the disclosure, there
is provided a method of driving an organic light-emitting display
device in which a plurality of data lines and a plurality of gate
lines are arranged and an image including a plurality of frames is
driven, the method including: a step of outputting a sensing
voltage in one frame section; a step of outputting a compensation
voltage in the one frame section; and a step of outputting a data
voltage in the one frame section.
According to the embodiments of the disclosure, it is possible to
provide a timing controller, an organic light-emitting display
device, and a driving method thereof that can prevent a degradation
in image quality.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
FIG. 1 is a diagram schematically illustrating an example of a
configuration of an organic light-emitting display device according
to embodiments of the present disclosure;
FIG. 2 is a circuit diagram illustrating an example of a subpixel
illustrated in FIG. 1;
FIG. 3A is a timing diagram illustrating a process of generating a
drive current in a subpixel;
FIG. 3B is a timing diagram illustrating a process of sensing a
threshold voltage in a subpixel;
FIG. 3C is a timing diagram illustrating a process of sensing
electron mobility in a subpixel;
FIG. 4 is a waveform diagram illustrating operations of the organic
light-emitting display device illustrated in FIG. 1;
FIG. 5 is a diagram illustrating a configuration of a data driver
illustrated in FIG. 1;
FIG. 6A is a waveform diagram illustrating an first example of a
signal which is output from the data driver illustrated in FIG. 5
to data lines;
FIG. 6B is a waveform diagram illustrating a second example of a
signal which is output from the data driver illustrated in FIG. 5
to data lines;
FIG. 6C is a waveform diagram illustrating a third example of a
signal which is output from the data driver illustrated in FIG. 5
to data lines;
FIG. 7 is a diagram illustrating an example of a configuration of
an image analyzing unit illustrated in FIG. 1; and
FIG. 8 is a flowchart illustrating a method of driving an organic
light-emitting display device according to the disclosure.
DETAILED DESCRIPTION
Hereinafter, some embodiments of the present disclosure will be
described in details with reference to the accompanying drawings.
In describing the disclosure with reference to the accompanying
drawings, the same elements will be referred to by the same
reference numerals or signs regardless of the drawing numbers. When
it is determined that detailed description of known configurations
or functions involved in the disclosure makes the gist of the
disclosure obscure, the detailed description thereof will not be
made.
Terms such as first, second, A, B, (a), and (b) can be used to
describe elements of the disclosure. These terms are merely used to
distinguish one element from another element and the essence,
order, sequence, number, or the like of the elements is not limited
to the terms. If it is mentioned that an element is "linked,"
"coupled," or "connected" to another element, it should be
understood that the element can be directly coupled or connected to
another element, still another element may be "interposed"
therebetween, or the elements may be "linked," "coupled," or
"connected" to each other with still another element interposed
therebetween.
FIG. 1 is a diagram illustrating an example of a configuration of
an organic light-emitting display device according to embodiments
of the present disclosure.
Referring to FIG. 1, an organic light-emitting display device 100
includes a display panel 110, a gate driver 120, a data driver 130,
and a timing controller 140.
The display panel 110 includes a plurality of gate lines GL1, . . .
, GLn and a plurality of data lines DL1, . . . , DLm which overlap
each other. The display panel 110 includes a plurality of subpixels
101 that are formed to correspond to areas in which the plurality
of gate lines GL1, . . . , GLn and the plurality of data lines DL1,
. . . , DLm overlap each other. Each of the plurality of subpixels
101 includes an organic light emitting diode (not illustrated) and
a pixel circuit (not illustrated) that supplies a drive current to
the organic light emitting diode. The pixel circuit is connected to
one of the gate lines GL1, . . . , GLn and one of the data lines
DL1, . . . , DLm and can supply a drive current to the organic
light emitting diode. Lines that are disposed in the display panel
110 are not limited to the plurality of gate lines GL1, . . . , GLn
and the plurality of data lines DL1, . . . , DLm.
The data driver 120 can supply a data signal to the plurality of
data lines DL1, . . . , DLm. The data signal corresponds to
grayscale and a voltage level of the data signal is determined
depending on the corresponding grayscale. The voltage of the data
signal is referred to as a data voltage. The data driver 120 can
supply a sensing signal to the plurality of data lines DL1, . . . ,
DLm. The voltage of the sensing signal is referred to as a sensing
voltage. When the voltage supplied to the organic light emitting
diode is lower than a threshold voltage of the organic light
emitting diode, a current does not flow in the organic light
emitting diode and the organic light emitting diode does not emit
light. In order to prevent a current from flowing in the organic
light emitting diode using the sensing voltage, the sensing voltage
can be set to a voltage lower than the threshold voltage of the
organic light emitting diode. The data driver 120 can sense a
voltage which is supplied to the organic light emitting diode.
The data driver 120 can supply a compensation voltage to the
plurality of data lines DL1, . . . , DLm. A voltage level of the
compensation voltage corresponds to the data voltage. The data
driver 120 can sequentially output the sensing voltage, the
compensation voltage, and the data voltage in one section.
Here, the number of data drivers 120 is illustrated to be one, but
the disclosure is not limited thereto. The number of data drivers
120 may be two or more depending on the size and the resolution of
the display panel 110. The data driver 120 can be embodied as an
integrated circuit.
The gate driver 130 can supply a gate signal to the plurality of
gate lines GL1, . . . , GLn. The subpixels 101 corresponding to the
gate lines GL1, . . . , GLn to which the gate signal has been
supplied can receive a data signal. The gate driver 130 can supply
a sensing control signal to the subpixels 101. The subpixels 101 to
which the sensing control signal output from the gate driver 130 is
supplied can be supplied with the sensing voltage output from the
data driver 120. Here, the number of gate drivers 130 is
illustrated to be one, but the disclosure is not limited thereto.
The number of gate drivers 130 may be two or more. The gate drivers
130 may be disposed on both lateral sides of the display panel 110,
one gate driver 130 may be connected to odd-numbered gate lines out
of the plurality of gate lines GL1, . . . , GLn, and the other gate
driver 130 may be connected to even-numbered gate lines out of the
plurality of gate lines GL1, . . . , GLn. However, the disclosure
is not limited thereto. The gate driver 130 can be embodied as an
integrated circuit.
The timing controller 140 can control the data driver 120 and the
gate driver 130. The timing controller 140 can supply sensing data
corresponding to the sensing signal and image data corresponding to
the data signal to the data driver 120. The timing controller 140
can sequentially output the sensing data and the image data in one
frame section. The sensing data and the image data can be digital
signals.
The timing controller 140 can correct a data signal and supply the
corrected data signal to the data driver 120. The operation of the
timing controller 140 is not limited thereto.
The timing controller 140 can be embodied as an integrated circuit.
The timing controller 140 can correct a data signal on the basis of
the sensing signal and supply the corrected data signal to the data
driver 120.
The organic light-emitting display device 100 according to the
disclosure may further include an image analyzing circuit 150
(which may be referred to herein as an image analyzing unit 150).
The image analyzing unit 150 analyzes image data, determines a
voltage level of a compensation voltage, and supply information on
the determined voltage level of the compensation voltage to the
timing controller 140. The image analyzing unit 150 is illustrated
to be an element separate from the timing controller 140, but the
disclosure is not limited thereto. The image analyzing unit 150 and
the timing controller 140 can be included in one integrated
circuit. The image analyzing circuit 150 may include any electrical
circuitry, features, components or the like configured to perform
the various operations of the image analyzing circuit 150 as
described herein. In some embodiments, one or more of the image
analyzing circuit 150 may be included in or otherwise implemented
by processing circuitry such as a microprocessor, microcontroller,
integrated circuit or the like.
FIG. 2 is a circuit diagram illustrating an example of a subpixel
illustrated in FIG. 1. FIG. 3A is a timing diagram illustrating a
process of generating a drive current in a subpixel, FIG. 3B is a
timing diagram illustrating a process of sensing a threshold
voltage in a subpixel, and FIG. 3C is a timing diagram illustrating
a process of sensing electron mobility in a subpixel.
Referring to FIG. 2, a subpixel 101 includes an organic light
emitting diode OLED and a pixel circuit that drives the organic
light emitting diode OLED. The pixel circuit includes a first
transistor M1, a second transistor M2, a third transistor M3, and a
capacitor Cs.
In the first transistor M1, a first electrode is connected to a
first node N1 connected to a first power supply line VL1 to which a
pixel high-potential voltage EVDD is supplied, a gate electrode is
connected to a second node N2, and a second electrode is connected
to a third node N3. The first transistor M1 can allow a current to
flow from the first node N1 to the third node N3 depending on a
voltage which is supplied to the second node N2. The first
electrode of the first transistor M1 may be a drain electrode and
the second electrode may be a source electrode. However, the
disclosure is not limited thereto.
The current flowing from the first node N1 to the third node N3
corresponds to Equation 1. Id=k(V.sub.GS-Vth).sup.2 Equation 1
Here, Id represents a quantity of current flowing from the first
node N1 to the third node N3, k represents electron mobility of a
transistor, V.sub.GS represents a voltage difference between the
gate electrode and the source electrode of the first transistor M1,
and Vth represents a threshold voltage of the first transistor
M1.
Accordingly, since the quantity of current varies depending on the
electron mobility and the deviation in threshold voltage, it is
possible to prevent degradation in image quality by correcting the
data signal on the basis of the electron mobility and the deviation
in threshold voltage.
In the second transistor M2, a first electrode is connected to the
corresponding data line DL, a gate electrode is connected to the
corresponding gate line GL, and a second electrode is connected to
the second node N2. The second transistor M2 allows a data voltage
Vdata corresponding to the data signal to be supplied to the second
node N2 depending on the gate signal supplied via the gate line GL.
The first electrode of the second transistor M2 may be a drain
electrode and the second electrode may be a source electrode.
However, the disclosure is not limited thereto.
In the third transistor M3, a first electrode is connected to the
third node N3, a gate electrode is connected to a corresponding
sensing control signal line Sense, and a second electrode is
connected to a second power supply line VL2 for supplying a first
initialization voltage VpreR or a second initialization voltage
VpreS. The first initialization voltage VpreR or the second
initialization voltage VpreS can initialize the voltage of the
third node N3. The first initialization voltage VpreR can
initialize the third node N3 when the data voltage Vdata is
supplied to the data line DL, and the second initialization voltage
VpreS can initialize the third node N3 when the sensing voltage
Vsense is supplied to the data line DL. However, the disclosure is
not limited thereto.
The voltage supplied to the third node N3 includes information
corresponding to a characteristic value of the subpixel 101.
Accordingly, it is possible to ascertain the characteristic value
of the subpixel 101 using the voltage of the third node N3 and to
compensate for the data signal. The characteristic value of the
subpixel 101 may be the threshold value of the first transistor M1,
the electron mobility, and deterioration information of the organic
light emitting diode OLED. However, the disclosure is not limited
thereto. The first electrode of the third transistor M3 may be a
drain electrode and the second electrode may be a source electrode.
However, the disclosure is not limited thereto.
The capacitor Cs is disposed between the second node N2 and the
third node N3. The capacitor Cs can keep the voltage of the gate
electrode and the voltage of the source electrode of the first
transistor M1 constant.
In the organic light emitting diode OLED, an anode electrode is
connected to the third node N3 and a cathode electrode is connected
to a pixel low-potential voltage EVSS. Here, the pixel
low-potential voltage EVSS may be a ground voltage. However, the
disclosure is not limited thereto. The organic light emitting diode
OLED can emit light depending on the quantity of current when a
current flows from the anode electrode to the cathode electrode.
The organic light emitting diode OLED can emit light of one color
of red, green, blue, and white. However, the disclosure is not
limited thereto.
A first switch RPRE and a second switch SPRE may be connected to
the second power supply line VL2. The first switch RPRE selectively
supplies the first initialization voltage VpreR to the second power
supply line VL2, and the second switch SPRE selectively supplies
the second initialization voltage VpreS to the second power supply
line VL2.
An analog-digital converter 120b may be connected to the pixel
circuit. The analog-digital converter 120b may be connected to the
second power supply line VL2. The analog-digital converter 120b is
supplied with the voltage of the third node N3 via the second power
supply line VL2 and converts the supplied voltage into a digital
signal. The analog-digital converter 120b may be connected to the
second power supply line VL2 via a third switch SAM. When the third
switch SAM is turned on, the analog-digital converter 120b can be
supplied with the voltage of the third node N3. The digital signal
which is converted by the analog-digital converter 120b is supplied
to the timing controller 140. However, the disclosure is not
limited thereto.
The circuit of a subpixel employed by the organic light-emitting
display device 100 is not limited thereto.
A process of supplying a drive current to an organic light emitting
diode OLED in a pixel circuit will be described below with
reference to FIG. 3A.
By turning on the first switch RPRE and turning on the third
transistor M3 using the sensing control signal Ssen which is
supplied via the sensing control signal line Sense, the third node
N3 can be initialized using the first initialization voltage VpreR.
Then, the first switch RPRE and the third transistor M3 are turned
off. When the second transistor M2 is turned on by the gate signal
GATE, the second node N2 is supplied with the data voltage Vdata.
The first transistor M1 can allow a drive current to flow from the
first node N1 to the third node N3 depending on the voltage between
the second node N2 and the third node N3. Accordingly, the drive
current can flow in the organic light emitting diode OLED depending
on the data voltage Vdata.
A process of sensing a threshold voltage in a pixel circuit will be
described below with reference to FIG. 3B.
First, the gate signal GATE is supplied to turn on the second
transistor M2 in a state in which a preset voltage is applied to
the data line DL. The preset voltage may be a sensing voltage
Vsense. When the second transistor M2 is turned on, a voltage
applied to the data line DL is supplied to the second node N2. The
first transistor M1 allows a current to flow from the first node N1
to the third node N3 depending on the voltage supplied to the
second node N2 and the voltage level of the third node N3
increases.
Then, the second switch SPRE is turned on. When the second switch
SPRE is turned on, the second initialization voltage VpreS is
supplied to the second power supply line VL2. When the sensing
control signal Ssen is supplied via the sensing control signal line
Sense after the second switch SPRE has been turned on, the third
transistor M3 is turned on. After the third transistor M3 is turned
on, the second switch SPRE is turned off. When the third transistor
M3 is turned on in a state in which the second switch SPRE is
turned off, the voltage of the third node N3 increases and the
third switch SAM can be turned on when a selected time elapses
after the increase of the voltage of the third node N3 has been
started. When the third switch SAM is turned on, the voltage of the
third node N3 is supplied to the analog-digital converter 120b. The
third switch SAM can be turned on at a time point at which the
voltage of the third node N3 does not increase any mode. At this
time, the voltage sensed by the analog-digital converter 120b is
compared with a preset voltage to sense the threshold voltage of
the first transistor M1.
A process of sensing electron mobility in a pixel circuit will be
described below with reference to FIG. 3C.
First, the gate signal GATE is supplied to turn on the second
transistor M2 in a state in which a preset voltage is supplied to
the data line DL. The preset voltage may be a sensing voltage
Vsense. When the second transistor M2 is turned on, the sensing
voltage Vsense supplied to the data line DL is supplied to the
second node N2. The third transistor M3 is turned on by the sensing
control signal Ssen. At this time, the second switch SPRE is turned
on. When the third transistor M3 and the second switch SPRE are
turned on, the second initialization voltage VpreS is supplied to
the third node N3.
The second transistor M2 is turned off by the gate signal and the
second switch SPRE are turned off. When the second transistor M2
and the second switch SPRE are turned off, the second node N2 and
the third node N3 are in a floating state. At this time, the first
transistor M1 allows a sensing current to flow to the second power
supply line VL2 via the third transistor M3 depending on the
voltage of the second node N2. The voltage of the second power
supply line VL2 increases due to the sensing current and the
voltage level of the third node N3 increases. At this time, the
second node N2 is connected to the third node N3 via the capacitor
Cs and thus the voltage level of the second node N2 also increases.
The voltage of the third node N3 increases with a certain slope and
this slope is indicative of the electron mobility. After a selected
time t1 has elapsed, the third switch SAM is turned on and
information on the electron mobility is supplied to the
analog-digital converter 120b.
FIG. 4 is a waveform diagram illustrating operations of the organic
light-emitting display device illustrated in FIG. 1.
Referring to FIG. 4, the organic light-emitting display device can
display an image including a plurality of frames. At this time, an
image corresponding to one frame can be displayed in each frame
section. The plurality of frames include a first frame section 1st
frame and a second frame section 2nd frame. Each of the first frame
section 1 st frame and the second frame section 2nd frame includes
a blank section and a display section. In the display section, a
gate signal is output and a data signal is supplied to display an
image.
The organic light-emitting display device 100 which is driven as
described above is supplied with black data not to display an image
in the blank section and is supplied with a data signal to display
an image in the display section. However, as illustrated in FIG. 2,
the pixel circuit includes the corresponding data line DL and the
second power supply line VL2, and the voltage supplied to the
second power supply line VL2 can be changed by the voltage supplied
to the data line DL. Accordingly, when the data line DL is supplied
with black data and then supplied with a data signal, the voltage
of the data line DL increases. Particularly, when a first data
signal is supplied to the data line DL, the voltage of the data
line DL increases. At this time, there may be a problem in that the
voltage of the second power supply line VL2 increases with the
increase of the voltage of the data line DL, the voltage level of
the first initialization voltage VpreR increases accordingly, and
the current flowing in the organic light emitting diode OLED is
affected to degrade the image quality.
FIG. 5 is a diagram illustrating a configuration of the data driver
illustrated in FIG. 1.
Referring to FIG. 5, the data driver 120 includes a digital-analog
converter 120a and an analog-digital converter 120b. The
digital-analog converter 120a is connected to the data lines DL and
the analog-digital converter 120b is connected to the second power
supply lines VL2. The digital-analog converter 120a and the
analog-digital converter 120b are illustrated to be connected to
one data line DL and one second power supply line VL2,
respectively, but the disclosure is not limited thereto.
The digital-analog converter 120a is supplied with image data RGB
from the timing controller 140. The digital-analog converter 120a
is supplied with black data Vblack and compensation voltage
information Vs_data corresponding to the compensation voltage VS.
The digital-analog converter 120a can generate and supply a data
signal, a black data signal, and a compensation voltage to the data
lines DL.
The analog-digital converter 120b can convert a voltage supplied
from the second power supply line VL2 into a digital signal.
FIG. 6A is a waveform diagram illustrating a first example of a
signal which is output from the data driver illustrated in FIG. 5
to the data lines, FIG. 6B is a waveform diagram illustrating a
second example of a signal which is output from the data driver
illustrated in FIG. 5 to the data lines, and FIG. 6C is a waveform
diagram illustrating a third example of a signal which is output
from the data driver illustrated in FIG. 5 to the data lines.
Referring to FIGS. 6A, 6B, and 6C, regarding the voltage output to
the data lines DL, the sensing voltage Vsense can be output in a
first section T1 after the black data voltage Vblack which is
supplied in the blank section has been output. Then, the
compensation voltage VS is output in a second section T2, and a
first data voltage Vdata1, a second data voltage Vdata2, and a
third data voltage Vdata3 are sequentially output in a third
section T3. The number of data voltages which are supplied in the
third section T3 is illustrated to be three (Vdata1, Vdata2, and
Vdata3), but this is for convenience of explanation and the
disclosure is not limited thereto. The number of data voltages
which are output in one frame section may correspond to the number
of gate lines of the display panel 110. The first section T1 and
the second section T2 can be included in the blank section in FIG.
4 and the third section T3 can be included in the display section.
The first to third sections T1 to T3 can be repeated.
Subpixels to which the sensing voltage Vsense is supplied in the
first section T1 may be all the subpixels of the display panel 110.
However, the disclosure is not limited thereto and the sensing
voltage may be supplied to subpixels which are selected using a
preset method in the first section. In the first section T1, the
electron mobility k of the first transistor M1 can be sensed using
the sensing voltage Vsense. However, the disclosure is not limited
thereto. The compensation voltage VS can be supplied in the second
section T2. Referring to FIG. 6A, the compensation voltage VS has a
preset voltage level. When the voltage level of the first data
voltage Vdata1 which is supplied in the third section T3 is lower
than the voltage level of the compensation voltage VS in a state in
which the voltage level of the compensation voltage VS is preset,
the voltage level of the data lines DL increases. When the voltage
level of the data lines DL increases, a problem may occurring that
the voltage level of the second power supply line VL2 to which the
first initialization voltage VpreS has been supplied also increases
due to a coupling phenomenon and the first initialization voltage
VpreS increases. Accordingly, a problem with a degradation in image
quality of the display panel 110 may occur. In addition, a problem
that the first initialization voltage VpreS decreases even when the
voltage level of the first data voltage Vdata1 is lower than the
voltage level of the compensation voltage VS.
However, as illustrated in FIG. 6B or 6C, the voltage level of the
compensation voltage VS corresponds to the first data voltage
Vdata1 which is supplied in the third section T3. That is, when the
voltage level of the first data voltage Vdata1 which is supplied in
the third section T3 is lower than the voltage level of the sensing
voltage Vsense as illustrated in FIG. 6B or higher than the voltage
level of the sensing voltage Vsense as illustrated in FIG. 6C, the
voltage level of the data lines DL becomes equal to the voltage
level of the first data voltage Vdata1 and is lower than or higher
than the voltage level of the sensing voltage Vsense by the
compensation voltage VS in the second section T2. Then, even when
the first data voltage Vdata1 is supplied to the data lines DL, the
voltage level of the data lines DL does not vary in the second
section T2 and the third section T3, and the voltage level of the
second power supply line VL2 does not vary.
FIG. 7 is a diagram illustrating an example of a configuration of
the image analyzing unit illustrated in FIG. 1.
Referring to FIG. 7, the image analyzing unit 150 includes a data
extracting circuit 151 (which may be referred to herein as a data
extracting unit 151) that extracts image data stored in a frame
memory 152, a lookup table 154 that stores compensation voltage
information on the voltage level of the compensation voltage
corresponding to the image data, and a data processing circuit 153
(which may be referred to herein as a data processing unit 153)
that is supplied with the compensation voltage information Vs_data
on the voltage level of the compensation voltage from the lookup
table 154 depending on the image data extracted by the data
extracting unit 151 and outputs the supplied compensation voltage
information. The data extracting circuit 151, the data processing
circuit 153, and the image analyzing circuit 150 may include any
electrical circuitry, features, components or the like configured
to perform the various operations of the data extracting circuit
151, the data processing circuit 153, and the image analyzing
circuit 150 as described herein. In some embodiments, one or more
of the data extracting circuit 151, the data processing circuit
153, and the image analyzing circuit 150 may be included in or
otherwise implemented by processing circuitry such as a
microprocessor, microcontroller, integrated circuit or the
like.
The frame memory 152 is supplied with image data RGB from an
external device (not illustrated), stores the supplied image data,
and supplies the stored image data RGB to the timing controller
140. The frame memory 152 can store image data RGB corresponding to
at least one frame. The data extracting unit 151 can extract first
data from the image data RGB stored in the frame memory 152. The
first data may be image data corresponding to the first data
voltage Vdata1 illustrated in FIGS. 6A and 6B. That is, the first
data corresponds to the data signal which is input to the subpixels
connected to the first gate line of the display panel 110. The
first data corresponds to a data signal which is input in a first
horizontal period. The data processing unit 153 is supplied with
the first data from the data extracting unit 151, is supplied with
the compensation voltage information Vs_data corresponding to the
compensation voltage VS corresponding to the first data stored in
the lookup table 154, and outputs the compensation voltage
information Vs_data. The compensation voltage information Vs_data
is supplied to the timing controller 140.
Here, the frame memory 152 is illustrated to be an element of the
image analyzing unit 150, but the disclosure is not limited thereto
and the frame memory may be an element separate from the image
analyzing unit 150.
FIG. 8 is a flowchart illustrating a method of driving an organic
light-emitting display device according to the disclosure.
Referring to FIG. 8, the organic light-emitting display device 100
includes a plurality of data lines and a plurality of gate lines,
and the organic light-emitting display device 100 drives an image
including a plurality of frames. The method of driving the organic
light-emitting display device 100 causes a sensing voltage to be
output in one frame section at S700.
A compensation voltage is output in one frame section at S710. The
voltage level of the compensation voltage corresponds to image data
which is input in one frame section. Image data is stored for each
frame in the frame memory, and the voltage level of the
compensation voltage is determined using the image data stored in
the frame memory. First data out of the image data stored in the
frame memory is extracted and the voltage level of the compensation
voltage corresponds to the first data. The first data may be image
data corresponding to a data signal which is first output to the
data lines in one frame section. The first data may be image data
corresponding to the first data voltage Vdata1 in FIGS. 6B and
6C.
A data voltage is output in one frame section at S720. Accordingly,
the sensing voltage, the compensation voltage, and the data voltage
are output in the same frame section. Since the data voltage
corresponds the voltage level of the compensation voltage which has
been previously supplied, the voltage level of the data lines does
not increase and the voltage level of the second power supply line
VL2 does not increase nor decrease. Accordingly, since the voltage
level of the first initialization voltage VpreR does not vary due
to the data signal which is supplied to the data lines, it is
possible to prevent a degradation in image quality from occurring
in the display panel 110.
A frame section corresponding to one frame out of a plurality of
frames includes a display section and a non-display section, a data
signal is supplied to the data lines in the display section, and a
sensing voltage and a compensation voltage are supplied in the
non-display section.
The above description and the accompanied drawings merely exemplify
the technical idea of the present disclosure, and various
modifications and changes such as coupling, separation,
substitution, and change of elements can be made by those skilled
in the art without departing from the essential features of the
disclosure. The embodiments disclosed in the disclosure are not for
restricting the technical idea of the disclosure but for explaining
the technical idea of the disclosure. Accordingly, the technical
scope of the disclosure is not limited by the embodiments. The
scope of the disclosure is defined by the appended claims, and all
the technical ideas within a range equivalent thereto should be
construed as belonging to the scope of the disclosure.
The various embodiments described above can be combined to provide
further embodiments. Further changes can be made to the embodiments
in light of the above-detailed description. In general, in the
following claims, the terms used should not be construed to limit
the claims to the specific embodiments disclosed in the
specification and the claims, but should be construed to include
all possible embodiments along with the full scope of equivalents
to which such claims are entitled. Accordingly, the claims are not
limited by the disclosure.
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